Held item

A held item (Japanese: 持ち物held item) is an item that may be carried by a Pokémon. This capability was first introduced in Generation II; however, when a Pokémon obtained in Generation I is traded to a Generation II game through the Time Capsule, it may be holding an item, such as a TM09 held by an Abra. Likewise, items held by Pokémon traded to Generation I will not be lost.

Gems

Incense

These items, when held by a Pokémon in the day-care, will cause it to produce an Egg that will hatch into a baby Pokémon introduced after Generation II. They will also affect the holder in various ways during battle.

Memories

‎Plates

Plates are ancient stone tablets engraved with text that increase the power of moves of a specific type. There is one for each type except Normal. Equipping a Plate to Arceus with Multitype will cause it to change type to that of the Plate held. The type of Judgment changes to match the type of the Pokémon's held Plate.

Z-Crystals

Z-Crystals are required to be held for performing Z-Moves. There is one for each type. Additionally, there are also specific Z-Crystals that, when held by specific Pokémon, will enable them to use their exclusive Z-Moves.